Field of the Invention
The present invention relates to a metallic covering for the roof of buildings, which is laid on an unventilated roof support, for example formed of rigid concrete forming a flat receiving surface. The covering is constructed of rigid plates, usually formed of metal preferably a corrosion-resistant metal such as zinc. The plates are designed to interlock in a mating fashion with each other forming troughs running in the direction of the slope of the roof. It also relates to right-angled supports for the covering in accordance with the invention.
Roof coverings in zinc are now employed for roofing or boarding or guttering in highly corrosive industrial environments and in very polluted urban environments. The roof frames for such roof coverings are in general no longer made of wood wood provided ventilation for high-priced or city roofs in previous centuries. The roof frames are now made of concrete which in theory constitutes a stronger, longer lasting material than wood. Numerous instances of corrosion in such roofs laid on supports in concrete have nevertheless been reported. Such corrosion is not only the result of the aggressive atmosphere to which such roofs are exposed but also results from the supports which are inserted between the metallic plates (zinc, copper, galvanized or stainless steel, aluminium, etc.) and which most commonly are not wood and comprise, rather, roofing felts and non-woven materials. These materials foater acid reactions when soaked with the aqueous medium resulting from condensation.
In order to overcome the difficulties currently encountered in coverings such as roofing, boarding or guttering constructed using rigid plates laid on unventilated and rigid supports, such as concrete sections, it appeared to be necessary to improve ventilation between the under part of the roof and the rigid plates in order to avoid condensation, and if the plates are formed of metal, to isolate them from the unventilated roofing support, particularly in the case where the support is is formed concrete, using a neutral material which is more resistant to acid and corrosive reactions in an aqueous medium.